No official word yet on a successor amid speculation that FX Networks' John Landgraf will expand his turf

After weeks of speculation about his future at the network, Kevin Reilly confirmed Thursday that he is stepping down as Fox Broadcasting entertainment chairman at the end of June.

No successor was named, but there’s been speculation that Fox Broadcasting COO Joe Earley will continue to take on more programming turf, as he already has during the past year. There’s also been talk — unconfirmed — that FX Networks chief John Landgraf may assume a level of oversight of Fox Broadcasting programming while maintaining his cable perch.

For the time being, Reilly’s lieutenants will report directly to Fox Networks Group chairman-CEO Peter Rice. Rice and Reilly sought to cast the decision as a mutual decision, but chatter about Reilly’s tenure has been ongoing for some time and picked up after the network had mixed reviews for its upfront presentation earlier this month. Still, word of his resignation caught most people on the Fox lot by surprise Thursday morning.

The shakeup at the flagship Fox broadcast network comes at a moment when James Murdoch is exerting more influence over Fox’s Hollywood operations, following his promotion to co-COO of 21st Century Fox alongside Chase Carey. Having a say in the key exec change at the Fox network will give Murdoch a prime chance to guide the network to its next iteration. As a Big Four network, Fox Broadcasting Co. maintains a high-profile within the company even if the cable division — chiefly FX and Fox News Channel — long ago eclipsed the broadcast net in terms of bottom-line contributions to the parent company.

Reilly told Variety that he had been thinking about his options for some time and had been discussing the transition with Rice. At a time when the media and television landscape is changing dramatically, Reilly said he’s been approached with some opportunities that he could not pursue while holding down an exec post at Fox.

“It’s an interesting landscape out there right now, and there are interesting things to be explored,” he said. “I’ve had some intriguing conversations over the last 12 months that got me thinking. But it’s not fair or right for me to be thinking about something else on the outside while I’m holding down this chair. Now I’ll be free to explore all of them.”

Although Reilly has had a rocky run in program development of late, the exec is well-regarded in the biz and has the benefit of strong relationships with creative talent. Those attributes are much in demand amid the expanding appetite for high-end programming among linear networks and upstart digital outlets.

Reilly would not elaborate on his plans but indicated he wanted to take some time during the summer to see what the market might bear. He assured that he is “not leaving the business” and noted that his resume includes stints in production (at Brillstein-Grey TV) and cable programming (FX) as well as his tenures at NBC and Fox.

Rice declined to comment on the changes afoot at Fox beyond a prepared statement expressing his gratitude to Reilly. Rice leaned on the TV vet after he moved from running the Fox Searchlight feature imprint to heading Fox Broadcasting in 2009. That shuffle was seen as a bid by Rupert Murdoch to give Rice exposure to television, which is the bedrock of 21st Century Fox’s worldwide operations, in preparation for a larger corporate role down the road.

“Kevin’s undeniable creative gift and passion for talent have left an indelible mark on our company, and we’re extremely grateful to him for his leadership, beginning with ‘The Shield’ and ‘Nip/Tuck’ at FX and continuing through ‘Glee,’ ‘New Girl,’ ‘The Following,’ ‘Sleepy Hollow’ and ‘Brooklyn Nine-Nine’ at Fox,” Rice said. “Kevin and I have been discussing his desire for a new challenge for some time, so while everyone at the network will miss his enthusiasm for adventurous television, we all respect his decision and agreed that after the upfront presentation was the right time. I’m personally extremely grateful to Kevin for his partnership during the past five years and look forward to working with him again in the future.”

Reilly’s decision to leave comes on the heels of his instigating a massive overhaul of the network’s development processes in an effort to yield better results from its programming R&D. In January, Reilly declared “RIP pilot season at Fox,” sparking an industry-wide conversation about the pros and cons of the traditional pilot process. Reilly championed the shift away from the network producing two dozen or more pilots during the January-April window — in favor of plotting pilot and script development on a year-round basis, and ather changes to decades-old network development dictums.

Reilly acknowledged that he is leaving with the job half finished at Fox, but said he felt the need to shake up the status quo was so great that he had to implement changes even though he was already thinking about moving on.

“Some things gnaw at you when you decide to move on,” Reilly said. “I just felt it was very important to start that dialogue. I didn’t think (changing the pilot production schedule) was a magic wand. Pilot season was just the tip of the iceberg in terms of some of the transformation that needs to happen in broadcast. I have set it in motion and god willing it will be a phenomenal catalyst for important changes. It would certainly be great if that change will continue but it will be somebody else’s boulder to push uphill. And change does not come easily.”

Reilly joined Fox in 2007 from NBC, where he was pushed out of his entertainment prexy post during one of Jeff Zucker’s re-engineering efforts at the Peacock. At first he was reunited with Peter Liguori, the exec that Reilly had worked with during their earlier tours of duty at FX. Reilly came to Fox as entertainment president and was upped to chairman under Rice in 2012.

Fox’s eight-year winning streak as the top network in adults 18-49 came to an end during the 2012-13 season, when it finished behind CBS. And in the just-concluded season, Fox managed to stay in second (this time behind NBC) but that was thanks to the Super Bowl and NFC Championship Game. In regular-program averages, Fox placed fourth this season — down 23% year-over-year and showing declines on every night of the week. The Wednesday/Thursday music competition series “The X Factor” and “American Idol” both took big tumbles, with the former getting canceled and the latter falling out of the top 10 for the first time. Other key shows like “Glee,” “New Girl” and “The Following” also saw meaningful declines.

Here is the memo Reilly sent to Fox staffers on Thursday:

To my friends and colleagues:

I have decided to resign as Chairman of Entertainment at FBC, effective at the end of June.

While difficult decisions have to be made every day, none have weighed more heavily on me than this. The inspired FOX leadership, coupled with your commitment to excellence at FBC, has provided one of the most rewarding chapters in my life.

I love TV. Always have. Since my mother told me to stop sitting so close and watching so much.

I couldn’t feel more fortunate to be afforded the opportunity to preside over a dynamic business, collaborate with the most creative people on the planet and drive culture. And also to be positioned at the nexus of change. It’s a fascinating moment in time as the digital evolution brings about radical shifts in consumer behavior. And through it all, the art form of TV has never been stronger or the marketplace more robust.

As invigorating as all that is to be a part of, we all know the daily feeding of the network beast and early morning ritual of waking to an overnight report card does breed a certain type of mania. My first boss, Brandon Tartikoff, described presiding over a broadcast network as “the worst best job in the world.” I remember coming up in the business and seeing how the grind turned some executives into grizzled cynics. And I vowed to never become that guy. I have always believed it’s incumbent upon network brass to bring a wide-eyed optimism to the chairs they rent. Talent deserves that. And frankly, the jobs are just no fun otherwise. Staying fresh and looking forward is part of why I feel the timing is right for me to turn the page now.

As you, my colleagues, know all too well, I am rarely satisfied. But I hope you all also know that I am very proud of what we have accomplished together and of the exceptional entertainment we have helped bring to fruition. We put shows and songs at the top of the charts, we took home trophies, we got out ahead of defining and building and measuring the multi-platform universe and we re-wrote rules about how to develop, program and market TV. And I think some of the best is yet to come next season. It’s been a satisfying blast.